The main objectives are, first, to identify and describe biologic and environmental determinants in the sequential decisions regarding marriage -pregnancy-childspacing, leading to various patterns of family structure. The second objective is to evaluate the consequences of family forming patterns on maternal health during pregnancy, social mobility of the family, and health and development of the child. These studies are based on extensive data collected in the Child Health and Development Studies. They contain a cohort study beginning with pregnant women at the time of their first prenatal clinic contact. They cover observations during pregnancy and delivery as well as observations on the children until they were at least 5 years old, and many of them more than 10 years old, and plans are being made to extend the studies into adolescence. The data are derived from interviews, medical records, and developmental examinations, and cover medical, demographic, sociologic and psychologic observations. The population is large enough--based on some 15,000 pregnant women--to allow extensive correlation studies and multifactorial analyses. Specifically, we anticipate the following studies: (1) description of childbearing and childspacing patterns in our population, and analysis of the determinants of family building patterns; and (2) causal analysis of the impact of these patterns for (a) health during pregnancy and delivery, as well as delivery outcomes, (b) the study of children's growth, health, and disease patterns, including utilization of equally accessible health care facilities, (c) physical and mental development at ages 5 and 10 years, including child's behavioral characteristics and parent-child relationships, and (d) family resources and labor force participation of women.